ABSTRACT
The extensive experimental data concerning the connection between transglutaminase and tumor growth make it necessary to discuss the topic by following the scheme of the multistage model of carcinogenesis. The action of tumor-promoting agents appears to result from their ability to increase cell proliferation, to alter cellular phenotype, or to induce genomic changes including the enhancement of malignant transformation. The increased genetic instability of the evolving cells in a tumor growing under the selective pressure of the host’s defense mechanisms leads to the appearance of heterogeneous cell populations. The possibility that a cellular transglutaminase can function outside of the cells in certain conditions has been a theoretical one so far and mostly related to the presence of dead cells in and around a tumor tissue. The induction of transglutaminases by tumor promoters represents a clear example of the relationship of transglutaminases to important cell regulatory mechanisms.
